The present invention is concerned with an improved sensing device for automatically guiding a self-propelled harvesting machine along a plant row, or along an analogous reference line, during a harvesting operation; and is more particularly concerned with an improved sensing device which is adapted to be mounted on the plant row divider structure which forms a portion of the harvesting mechanism at the front end of the machine, and which cooperates with a transducer responsive to movement or deflection of the feeler as it engages plants in a row to generate a control signal for the automatic steering system of the harvester.
In one known arrangement of the general type described above, feelers have been provided which are mounted externally of the divider points of the plant harvesting mechanism. A securing link is provided at the front and to one side of the divider for each feeler; and the feelers, although angled to provide sufficient spacing from their respective divider points, are each formed as substantially straight elements which extend rearwardly in generally parallel relation to the side walls of their respective divider points. The rearward end of each feeler is supported on its respective divider by a spring, and is connected to this location to an electric switching device for control of the automatic steering system of the harvester.
In this known arrangement, the feelers mounted on the sides of the dividers are adapted to sense a row of plants from both sides thereof, but the arrangement is such that each feeler is adapted to contact only a single stalk in the row at any given time so that the feelers, during a control operation, must jump from stalk to stalk. As a result, a regular jerking of the automatic steering system on the harvester occurs. Furthermore, this known arrangement exhibits the disadvantage that, due to the fact that all connections to the feeler are external of its associated divider point, proper operation of the feeler and of the coupling elements and electrical switch members associated therewith, is often impaired by portions of plants, or lumps of earth or stones, which tend to lie between the feelers and divider points or which cause mechanical damage to the exposed elements. The link connections on the feelers in this exposed arrangement are, moreover, subject to continual wear, which gives rise to problems of maintenance and repair; reverse operation of the harvester causes additional problems since plants tend to be caught in the region behind the outer ends of the feelers, which cannot correspondingly yield; and, in addition, the relay control used in this known sensing device requires a large amount of space within the divider point.
An alternative sensing device has been suggested heretofore which is intended to eliminate some of the defects noted above. In this alternative device, the feelers are carried rigidly on an arm which extends forwardly, in the direction of travel of the harvester, beyond the cutting elements of the harvesting machine. The feelers employed are secured at the front end of this arm, and extend rearwardly in a shallow arc so that they contact simultaneously at least two stalks in a given plant row. A flexible strip measuring element, which converts bending of the feeler into an electrical signal, is situated on the feeler near its point of attachment to the arm. This arrangement also exhibits a number of disadvantages. It is, for example, subject to heavy mechanical stress, especially at high speed, which requires that the flexible measuring element employed be situated on the unfavorable sensing side of the feeler. Moreover, the problem of reversing motion of the harvester machine remains unsolved, since there is the danger that the rigidly secured feelers in this type of sensing device will be bent when the harvester is moved in a reverse direction.
The present invention is intended to obviate all of these problems by provision of a sensing device of the type first mentioned, i.e., wherein the feelers are mounted on the divider points of the harvester mechanism, but wherein the feelers are mounted in a protected arrangement and are so coupled with associated transducers that the individual mechanical influences resulting from resistance to motion are effective only at the free ends of the feeler which, in turn, is adapted to yield pivotally.